Valeoscope Commercial Vehicles Clutch 2020

Diagnosis Clutch slippage or lack of torque capacity

6. Stripped yarn after destruction of facing binder

8. Broken pressure plate

7. Burst facing

9. Seized tube-guide/seized sleeve

Parts inspection ●● Burst of facing on either one side or two sides of the clutch disc. ●● Friction of rivets against pressure plate and flywheel. Vehicle behavior ●● Slippage of clutch, the vehicle suddenly stops.

Parts inspection Release bearing sleeve seized on tube-guide or plastic sleeve destroyed. Vehicle behavior ●● Wrong release of the clutch ●● Hard gear shifting ●● Unsmooth engagement ●● Premature wear of the facings

Stripped yarn after destruction of facing binder

Broken pressure plate

Parts inspection There are breaks on the pressure plate. Vehicle behavior ●● It is impossible or difficult to shift gears ●● Slippage of the clutch. Reasons ●● Wrong conditions or wrong adjustments of the clutch linkage ●● Excessive slippage Diagnosis ò ò Long time slippage increases the temperature of the pressure plate friction surface (>700°C) but the opposite side is in contact with clutch housing ambient air (from 100 to 150°C). Under such temperature gradients, the pressure plate deformation will exceed the mechanical resistance of the pressure plate. ò ò Such issues happen when the clutch linkage is damaged or because of fast facing wear. ò ò The clutch torque capacity is not enough because of the pressure plate load reduction. Attention Ɂ Ɂ The centrifugation of the pressure plate can damage other vehicle components (clutch housing, gearbox…). Ɂ Ɂ Check periodically the facings wear indicators when they are available in the vehicle. Advice  ąą Replace the worn parts of the clutch linkage and adjust it accordingly to the manufacturer’s instructions. ą ą Replace the 3 parts of the clutch kit. 

Parts inspection The organic type facings are burned or destroyed. Vehicle behavior ●● Slippage of clutch. ●● Usually, the vehicle is off the road. Reasons ●● Clutch is operated in severe condition: overload, towing, and vehicle stuck in mud… ●● Clutch used frequently in severe situations: off road, earth moving, agriculture vehicle. ●● Friction material is not suitable for the vehicle. Diagnosis ò ò Destruction of yarn binder, due to very high temperatures (> 450°C). ò ò The clutch was used while the facings had reached the wear limit; it reaches a high temperature because of excessive slippage time. Attention Ɂ Ɂ Check periodically the wear status of the facings (if possible). Advice  ą ą Check the conditions of the flywheel (thermal cracks, overheated areas…), ą ą Re-machine the flywheel or replace it if necessary. ą ą Check the ring gear position. ą ą Replace the 3 parts of the clutch kit. 

Burst facing

seized tube-guide / seized sleeve

Reasons ●● High temperature facing deterioration or important facing wear. Weak facings (Binder destroyed or thickness too low). ●● Use of repaired clutch discs. ●● Mis-shifting. ●● Gearbox speed range switch is in wrong position. ●● The rotation speed of the gearbox input shaft is too high (rpm overrun). Diagnosis ò ò The centrifugal force is higher than the mechanical resistance of the facings. Attention Ɂ Ɂ Always start the vehicle in first gear to protect the clutch. Advice   Valeo designed the facing bonded on steel-back to improve its burst resistance and to increase wear capacity. With the widespread use of robotised gearbox, steel-back is not necessary as there is no possible gear shift error in this case.

Reasons ●● The release bearing travel is short; therefore the clutch is not completely released. ●● Clutch linkage is tough and the release bearing speed is slow during re-engagement. This increases the clutch slipping time. ●● The movement of the release bearing cannot be precisely controlled. Diagnosis ò ò Insufficient quantity of grease for sleeve (reservoir not fully filled). ò ò Inappropriate grease (too fluid). ò ò Wrong conditions of the tube-guide. ò ò Non symmetrical fork contact. Advice   Replace the release bearing and when necessary the tube-guide.  Replace the fork if necessary (worn contact areas).

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